Coalescence Scavenging Drives Droplet Number Concentration in Southern Ocean Low Clouds
Coalescence Scavenging Drives Droplet Number Concentration in Southern Ocean Low Clouds
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DOI：
10.1029/2022gl097819
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发表时间：
2022-01
影响因子：
5.2
通讯作者：
Litai Kang;R. Marchand;R. Wood;I. McCoy
中科院分区：
文献类型：
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作者：
Litai Kang;R. Marchand;R. Wood;I. McCoy
云滴数浓度（Nd）是一个重要的微物理特性，它在很大程度上取决于作为云凝结核（CCN）的气溶胶源和汇之间的平衡。尽管是一个关键的汇的云凝结核，聚结清除南大洋（SO）云的影响知之甚少。我们应用一个简单的源-汇预算模型的基础上参数化南夏季飞机观测测试模型的行为和检查的相对影响的过程，确定Nd在SO层积云。该模型预测钕与小的偏差和相关系数为0.7相比，观测。聚结清除被认为是CCN在液相和混合相沉淀层积云中的重要汇，并根据沉淀速率将预测的Nd减少多达90%。在南半球夏季，对流层自由气溶胶源对Nd的控制作用强于地面气溶胶源。
Cloud droplet number concentration (Nd) is a key microphysical property that is largely controlled by the balance between sources and sinks of aerosols that serve as cloud condensation nuclei (CCN). Despite being a key sink of CCN, the impact of coalescence scavenging on Southern Ocean (SO) cloud is poorly known. We apply a simple source‐and‐sink budget model based on parameterizations to austral summer aircraft observations to test model behavior and examine the relative influence of processes that determine Nd in SO stratocumulus clouds. The model predicts Nd with little bias and a correlation coefficient of ∼0.7 compared with observations. Coalescence scavenging is found to be an important sink of CCN in both liquid and mixed‐phase precipitating stratocumulus and reduces the predicted Nd by as much as 90% depending on the precipitation rate. The free tropospheric aerosol source controls Nd more strongly than the surface aerosol source during austral summer.